As the size of features in semiconductor devices continue to shrink, there is a continuing need to improve quality of the individual deposited layers comprising a semiconductor device. Some quality problems, for instance, uniformity of a layer across a substrate can be attributed to the geometry of the process chamber in which the layer is formed or processed. For example, pump ports are often disposed asymmetrically with respect to the chamber volume, which can result in azimuthally non-uniform pumping proximate the surface of a substrate being processed. A process gas being supplied to the substrate via a gas inlet disposed centrally above a substrate support is often distributed non-uniformly across the substrate surface, having thinner deposition proximate the pumping port.
Many techniques, for example, Physical Vapor Deposition, Chemical Vapor Deposition and Atomic Layer Deposition (ALD) are well known for the fabrication of devices using thin layers. The ALD technique deposits extremely thin coatings on the substrate surface. As such, ALD techniques are especially susceptible to non-uniform distribution of process gas causing non-uniform layer deposition.
Thus, there is a need in the art for an improved process chamber for providing improved uniformity in the distribution of a process gas across the surface of a substrate.